This invention deals with industrial rotary shredders. Rotary shredders are very well known devices which are used to comminute waste materials for purposes of reducing the bulk of such waste material and/or to more easily facilitate recycling of such materials.
In general, conventional rotary shredding devices are provided with a pair of parallel, horizontally spaced-apart, cutter shafts one or both of which may be mounted on drive shafts, a series of alternating disc-type cutters and spacer elements equally spaced-apart along the shaft axes. The cutter discs on the shafts are interdigitally placed along the shafts. That is, the cutter discs on the shafts are fixed at a position along the shaft axis so that they extend into the space between the cutters on the other shaft, i.e., into the spaces between the cutter discs established by the spacer discs.
The cutter shafts are counter-rotated so that the upper portions of the cutter discs on the two shafts rotate toward each other to force material fed into the device from above, downwardly, between the two shafts where the material is shredded in the nip created by the interdigitized cutter and spacer elements. Reference can be made to FIG. 1 of this specification for a prior art configuration of such a cutting chamber of such a device.
As can be observed from FIG. 1 of this application, prior art rotary shredders are typically provided with a plurality of immovable, or firmly attached finger elements which extend inwardly toward the cutter/spacer discs to strip shredded material from the cutter and spacer discs to thereby prevent such shredded material from wrapping around the cutter shafts and overloading the shaft drives, and hence overloading the driving motors and other apparatii of the device.
One reference that deals with the problems of jamming in the shafts of the rotary shredder is U.S. Pat. No. 5,285,973, issued Feb. 15, 1994 to Goforth, et al, in which a shredder is described which utilizes side support bearings which are affixed to the walls of the cutting chamber and act to support the shaft, while preventing the flow of comminuted material between the cutters and thus preventing wear on the cutter discs. It should be noted that the support bearings, even though providing the needed clearing away of comminuted material, are bolted or otherwise affixed to the apparatus such that the equipment has to be torn down to replace such support bearings.
In another such reference, U.S. Pat. No. 5,516,050, issued May 14, 1996 to Yamamoto, et al, there is shown rows of finger blocks mounted to a frame body of a rotary industrial shredder, laterally parallel to rotating shafts. The fingers are provided to maintain tight clearances between the fingers and the cutters of the rotary shredder. It should be noted that the patentees therein, at column 3, lines 37, et seq. state that the importance of their invention is the opposed series of finger blocks which are mounted to the frame body laterally parallel to the shafts and in opposition to the series of cutter/spacer discs. The finger blocks are mounted between a pair of parallel, vertically separated upper and lower positioning bars, and are rigidly attached to the inside lateral face of the frame body. Thus, the finger bars are rigidly clamped between the two parallel bars, which requires that one of the parallel bars has to be detached before the finger blocks can be moved, removed and/or replaced.
Finally, there is shown in U.S. Pat. No. 5,609,307, which issued on Mar. 11, 1997 to Rota, a shredding apparatus in which there is employed "cleaning sectors" which are fixed to the frame of the apparatus, which cooperate with a slower rolling pair of cooperating rollers having cutting discs. These cleaning sectors provide for a comb-like arrangement to clean between the rotating cutting discs.
Each of these prior art devices provide for cleaning between the cutting discs, but all require that the cleaning devices be fixed to the walls or frame of the device, requiring extended down time in order to remove and replace worn or defective parts.